Advertisements All this talk about 4TB upgrades but opening an external drive and cancelling the warranty didn't seem like the way to go. Lacking any other experience, I decided to go with the Toshiba MQ03ABB300 3TB 2.5 inch drive with a 3 year warranty. The hardest part was opening the Tivo. The first time I got a boot failure with no error messages, just repeated reboots. The second time I found the SATA cable at the motherboard had popped off (note to Tivo - locking cables are cheap). I rebooted, the Tivo formatter did it's thing, completed setup and updates, and I had a big working Tivo! To top it all off, System Information says I have 478 hours of HD and 3289 hours of SD. I can only guess that is because I stuck with Tivo's native format. If anyone has a better explanation, I would love to hear it. One other note, the security screw is a T8 torx security, not a T10. I was able to get it out with a regular torx bit and did not put it back in. The internal screws are regular torx T10.